Fatigue Behavior of Welded High-Strength Steels

Department of Aeronautics Report No. 97 – 30

Royal Institute of Technology – KTH- Stockholm Sweden

The Thesis deals with the fatigue strength of welded high strength steels. As very well understood the fatigue strength of welded connections done with high-strength steel do not allow for the increase of the fatigue design stresses and as a result of this the plate thickness cannot be reduced. The reduction of plate thickness will include the reduction of own weight and/or the increase of pay-load. Hence, the use of high-strength steel is limited in structures subjected to fatigue loads. To come around this situation fatigue life improvement techniques have been studied and compared in depth in order to select the one which is most suitable in terms of applicability, benefits and costs.

The analysis of the fatigue test results of improved welds done with various steel grades showed the increased benefit of the improvement techniques for higher steel grades.